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Irrational or just wary?

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Numerous psychological articles have claimed to demonstrate human “irrationality,” but Craig R. M. McKenzie, John T. Wixted, and David C. Noelle suggest that these studies have made one crucial assumption. When subjects demonstrate behavior (predictable or unpredictable), researchers believe that the subjects believe the assumptions or parameters underlying the purported normative response. Hence unpredictable behavior would be due to irrationality on the part of the subject. McKenzie et al. argue that people are in fact quite rational in such circumstances as exhibiting unpredictable behavior; they simply don’t trust what people in lab coats tell them. Accounting for participant doubt concerning the legitimacy of explicit key task parameters from the start of an experiment is more effective than trying to convince subjects that what they are being told is true.

“Many purported demonstrations of irrational behavior rely on the assumption that participants believe key task parameters that are merely asserted by experimenters. For example, previous researchers have found that participants who first reported confidence in items presented in a yes–no format did not change confidence to the degree prescribed by the normative model when those same items were later presented in a forced-choice format. A crucial assumption, however, was that participants fully believed the assertion that the forced-choice items were mutually exclusive and exhaustive. In this article, the authors derive and test a new normative model in which it is not assumed that participants fully believe the assertion. Two visual identification experiments show that the new normative model provides a compelling account of participants’ confidence reports.”

Complete article

“In essence, all information is imperfectly reliable, and information provided to participants by experimenters is no exception. Indeed, experimenter-provided information might be less trustworthy than most. Participants are often deceived in psychology experiments, and they are aware of this.”

“In many tasks, participants’ behavior is compared to a normative standard, and differences between behavior and the normative response are routinely interpreted as errors … If participants do not fully believe key task parameters, which are often merely asserted by experimenters, then calling their responses ‘errors’ would be misleading.”

“The idea that participants may not fully believe key task parameters is not one that is generally taken into consideration in experiments designed to assess whether participants behave in a normative manner. Often, researchers arrive at the conclusion that participants do not behave normatively, just as McKenzie et al. (2001) did. Not only does our proposed approach make salient various assumptions experimenters might otherwise take for granted, but it also highlights the fact that there are often multiple normatively defensible responses to a given situation.”

“We mention just one more example. Ross, Lepper, and Hubbard (1975) presented participants with pairs of suicide notes, one of which was said to be authentic and one of which was said to be inauthentic. Participants were to judge which note was authentic for a series of such pairs and, after each judgment, received feedback. All participants received predetermined (i.e., false) feedback, indicating either that most of their judgments were correct or that most were incorrect … Note the participants’ quandary after being told they had been deceived (“Were they lying to me then, or are they lying to me now?”), and any skepticism about what the experimenter said about the false feedback leads to results that the authors consider irrational … The initial debriefing was also part of the experiment, and participants were deceived then, too. It was only during the final debriefing that participants were told the true purpose of the experiment. Maybe the only irrational thing to do in any experiment is to fully believe anything the experimenter tells you.”

“We believe it is best to accept participant skepticism as an important—and tractable—variable in laboratory experiments, especially those that compare behavior to a normative standard. The success of the trust model in the present context shows that it is both desirable and feasible to develop normative models in which it is not assumed that participants believe key assumptions that are often taken for granted by experimenters.”

About the Authors:

David C. Noelle


Currently David C. Noelle is assistant professor of computer science and assistant professor of psychology at Vanderbilt University. He is also working as a postdoctoral researcher at the Center for the Neural Basis of Cognition. He received his PhD in Cognitive Science and Computer Science from the University of California, San Diego (UCSD) in 1997. His research interests include artificial intelligence, machine learning, and cognitive modeling using connectionist techniques. He is also interested in modeling “high level” cognitive processes using “low level” artificial neural network models. Noelle’s current research is focused on connectionist models of rule guided behavior and learning from direct instruction.

David C. Noelle home page

Craig R. M. McKenzie


Craig R. M. McKenzie is an associate professor at the University of California, San Diego. He received his Ph.D. in Psychology from The University of Chicago in 1994. McKenzie is a cognitive psychologist interested in inference, uncertainty, and choice. Most of His recent research explains errors people purportedly make in the laboratory by (a) adopting a different (usually Bayesian) normative approach to the task of interest and (b) taking into account the typical structure of the environment. “I often find that “errors” are the result of people behaving as (qualitative) Bayesians who make reasonable assumptions about task parameters that reflect how the world usually works.” He doesn’t claim that people never make mistakes, only that people’s behavior is much richer, more interesting — and often more rational — than usually depicted in the judgment-and-decision-making literature.

Craig R. M. McKenzie home page

John T. Wixted


Presently John T. Wixted is professor & chair of the Department of Psychology at The University of California at San Diego. He earned his Ph.D. in clinical psychology from Emory University in 1987. His research interests mainly involve signal-detection models of recognition memory and the psychology and neuroscience of forgetting, but “I maintain a connection to my clinical background by teaching Abnormal Psychology on a regular basis”.

John T. Wixted home page


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